Enhancing the thermoelectric performance of CoSb3-based skutterudite by decoupling the electrical and thermal properties by embedding Cu nanoparticles

Abstract Co0.91Ni0.09Sb3 embedded with Cu nanoparticles (NPs) was synthesized by applying a hydrothermal process followed by spark plasma sintering. The effects of Cu NPs on the electrical and thermal transport properties of the Co0.91Ni0.09Sb3 matrix were investigated in the temperature range of 303–773 K. Cu NPs introduced into the Co0.91Ni0.09Sb3 matrix slightly decreased the electrical conductivity and significantly enhanced the Seebeck coefficient by the energy filtering effect, leading to an improved power factor at 773 K. Furthermore, a significant decrease in the thermal conductivity was realized by increasing the number of grain boundaries. These favorable effects contributed to the improvement in ZT to a value ~57% higher than that of pristine Co0.91Ni0.09Sb3. The highest ZT value of 1.02 was achieved by incorporating 4.5 wt% of Cu NPs in Co0.91Ni0.09Sb3 at 773 K. Thus, decoupling the electrical and thermal transport properties of thermoelectric materials is a viable strategy for optimizing the ZT value.